Germicidal composition comprising a 3, 5-dimethyl-4-nitrosopyrazole



Patented June UNITED STATES PATENT OFFICE 2.510.124. a

1 GER D HCIDA L COMPOSITION COMPRISING 'A 8,5-DDIETHYL-4-NITROSOPYRAZOLE Norman K. Snndhoim, Naugatuck, Conn, assignor to United States Rubber Company, New York,' N. Y., a corporation of New Jersey No Drawing. Application February 12, 1947, Serial No. 728,192

Claims. (CI. 16743) invention relates to new and useful improvements in germicideathat is, fungicides and bactericides. The invention further relates to methods of treating plants, and to methods of protecting organic material subject to attack by microorganisms, as the immunizing of seed, and the mildewproofing of fabrics and other material.

I have found that 4-nitrosopyrazoles'are effective fungicides and bactericides. The structure of the parent compound. -nitrosopyrazole, may be represented as follows:

.Two methods for the preparation of i-nitrosopound with nitrous-acid or with a nitrous'acid ester and alkali. Because acetylacetone is the most readily available ,beta-diketone and as monoarylhydrazines such as phenylhydrazine and 'p-chlorophenylhydrazine are easily prepared,

these materials-are of particular value in the Also, the 1-aryl-3,5-dimet hyl-4enitrosopyrazoles prepared from these materials exhibit exceptional fungicidal activity. The hydrogens in the 1, 3, and 5-positions of the parent. 4-nitrosopyrazole may be substituted by univalent radicals, such as alkyl, cycloalkyl, aryl, and aralkyl radicals, and the hydrogen in the 5-position may be substituted also by alkoxy and secondary amino radicals to give various i-nitrosopyrazoles which have been found as a class to be effective fungicides and bactericides.

The i-nitrosopyrazoles may be used as seed protectants and disinfectants, and to protect plants, which term includes plant parts, or soil I I from microorganisms harmful to seeds and plants.

They may also be applied to prevent or retard fungus growth and'the formation ofmildew on organic material, such as wood, fur, rope, hair,

feathers, cotton, wool, synthetic organic fibers.

80 and the like. They may be applied as a dust, as

85 solvent, for example, water.

in admixture'with a solid carrier, such as. clay or talc, or they may be applied as a liquid or spray in a liquid carrier, as in solution in a suitable solvent, or suspendedin a suitable non- Preferably when applied in aqueous suspension, the composition contains a dispersing agent for the chemical. In

seed treatment, the i-nitrosopyrazoles are preferably applied to the seed, as by tumbling with the chemical alone or admixed with a powdered solid carrier. In foliage treatment, the 4-nitrosopyrazoles :are preferably applied to the plant parts by spraying with an aqueous suspension of the simhemicalcontaining dispersing agent. The

gels may be applied to foliage by the aerosol mthod. Solutions for the aerosol treatment may be prepared by dissolving the chemical directly in the highly volatile liquid carrier or first dissolving the chemical in a less volatile solvent and then admixingsuch solution with the highly volatile liquid aersol carrier. The 4-nitrosopyrazoies may be used admixed with carriers that are active of themselves, for example, other fungicides or bacetericides, insecticides, insectipreparation of the compounds of this invention. fuges, fertilizers, hormones.

Examples of 4-nitrosopyrazoles, which are new compounds. and their preparation, are as follows:

1- (l-chlorophenyl) -3,5-dimethul- 4-nitrosoiwrazole A suspension of 5 g. of acetyiacetone in a mixture of 50 cc.-of water and 4.5 cc. of concentrated I to it with stirring. The green solid which sepsrated was filtered oil. and dried; the yield was 4 g. The product melted at 118 C. Anal. calculated for CuHioClNsO: N, 17.84; Found: N, 17.70. 17.56.

The 3,5-dimethyl-4-nitrosopyrazoles below were similarly prepared from isonitrosoacetylacetone and the required hydrazine.

1-(4-nitrophenyl)-3,5-dimethyl- 4-nitrosopyrazole This compound was prepared from p-nitrophenylhydrazine and' isonitrosoacetylacetone. The product was recrystallized from alcohol to give green crystals, M. P. 134 0. Anal. calculated for CnHmNsOc: N, 22.76; Found: N, 22.23.

1- (o-napthyl) -3,5-dimethyl-4-nitrosomrazole This compound was prepared from s-naphthylhydrazine and isonitrosoacetylacetone; green crystals from alcohol, M. P. 88-89 (J. .Anal. calculated'tor CrsHmNaO: N, 16.78; Found: N. 16.57.

1- (2,4-dichl0rophenul) -3,5-dimet7wl-4- nitrosowmzole This compound was prepared from 2,4-dichlorophenylhydrazine and isonitrosoacetylacetone: green crystals from alcohol, M. P. 89-90 C. Anal. calculated for CuHsChNaO: N. 15.57: Found: N, 15.64. 15.48.

1-(2,5-dichlorophenyl) -3,5-dimethyl-4- nitrosopm'azole This compound was prepared from 2,5-dichlorophenylhydrazine and isomtrosoacetylacetone: green crystalsfrom alcohol, M. P. 99-100 0. Anal. calculated for CnHsClzNsO: N, 15.67: Found: N,- 15.26, 15.39.

1-(4-tcrt-amylphenyl) -3,s-dmemvz-4-' nitrosopzlrazol This compound was prepared from p-tertamylphenylhydrazine and isonitrosoacetylacetone; green crystals from alcohol, M. P. 92-93 C.

Anal. calculated for CuHaNsO: N, 15.5: Foundi as 1- (bourbon/menu!) -s,s-a1me1 nul -s-.

pitrosopymzole This compound was prepared from p-hydra- The product was recrystallized from alcohol to give a green-blue solid which does not melt below 220' C. However, above 120 C; the compound slowly turns brown. Anal. calculated for 4 CuHuNaOs N, 17.14; Found: N. 16.95.

The copper salt (of 1-(4-carboxyphenyl)-3,5- .dimethyl-4-nitrosopyrazole was prepared by adding a solution or $5 mol of cupric suli'ate to a solution or 1 mol of the sodium salt of the acid. The brown precipitate was filtered oi! and dried.

1-(4-thi0cvan0pheayl) -3,5-dimethy'l-4- l0 nitrosopyrazole This compolmd was prepared from p-thiocyanophenylhydrazineand isonitrosoacetylacetone; green crystals from alcohol, M. P. 105' 0. Anal. calculated for CnHicNsOS: N, 21.71: 8.

12.40; Found: N, 22.20; 12.82.

l-(l-suilamylphenvll-3,5-dimethfll-lnitrosopyrazolc This compound 'was prepared from 4-hydra- 2o zinobenzenesuli'onamide and isonitrosoaeetylacetone; green crystals from alcohol. decomposes at 198 0.. Anal. calculated for 0111111114018: 8, 11.4: Found: 8.11.7. I

z-m-onz ro rmvnassistant-4- nitrosom/razole This compound was prepared from m-chlorophenylhydrazine and isonitrosoacetylacetone: light green crystals from alcohol, M. P. 84' C.

' Anal. calculated for C11HmClNsO: c1, 15.1; Found:

l -(o-chloropherwl) -3,5-di1neth1ll-4- nitrosopw'azolc This compound was prepared from o-chlorophenylhydrazine and isonitrosoacetylacetone:

blue crystals from alcohol, M. P. 117 0. Anal.

glalclilated fOr-CnHroClNaO: Cl. 15.07; Found:

nitrosopurazole This compound was prepared from p-iodophenylhydrazine and isonitrosoacetylaceton'e: green 5 crystals from alcohol. M. P. 112 C. Anal. calculated i'or cnmonao; N, 12.84; Found: N, 12.61.

l-(l-fluorophenyl) -s,s-aimotnvz-4A v nitrosopvrazole,

compound was vprepared from p-iluorophenylhydrazine and isonitrosoacetylacetone;

b u reen crystals, M. P. -117- c. Anal. calculated .ior CuHmFNsO: 11.19.18; Round: N,,18.91

as "14114211111)-3,5-dimethul-4-nitrosopwazole This compound was prepared from 4-hydrszinobiphenyl and isonitrosoacetylacetone: green I i-u-n-outvzpn im 4.54.51. .51..-

itr w m e'yi This compound was prepared from 4-n butylv phenylhydrazine and 'isonitrososcetylacetone. "The product is a darkgreen oil. j 1 :11. sinobenzoic acid and isonitrosoacetylacetone.-

1- (l-chlorophenul) -3-metliw'l -4 -n itroso-5- n-herulpvrazole.

Heptanoylacetone was prepared by treating a "mixture of ethyl acetate and methyl n-hexyl centrated hydrochloric acid and 500 cc. of water.

A blue oil was produced. The blue oil was separated from the aqueous layer by extraction with ether.. The ether solutionwas dried with anhydrous sodium sulfate and the ether removed by distillation. A dark green oil remained. It weighed 26 g.

1,3,5 -trimethyl-4-nitrosopyrazole A solution of 4.9 g. of sodium nitrite in 20 cc. of water was added to a cold stirred mixture of 'I g. of acetylacetone, 6 cc. of concentrated hydrochloric acid and 70 cc. of water. The result ing solution was slowly added to a solution of 7.4 g, of sodium carbonate and 10.1 g. of methylhydrazine sulfate in 100 cc. of water cooled to 5 C. The mixture was stirred in ice for two hours, the blue solid product filtered oil and the product dried. It melted at 80-81 C. Anal. calculated for CsHaNaO; N, 30.2; Found: N, 29.1.

. Literature references to the preparation of various 4-nitrosopyrazoles which are old compounds, and on which germicidal tests are reported in the tables below, are as follows:

(see

1-phenyl-3-methyl-4-nitroso 5 methylanilinopyrazole (also :called knitrosopseudoanilinopyrin) (see Michaelis and Mielecke, Ber. 40, 4482).

The following examples of the effectiveness of the various 4-nitrosopyrazoles as fungicides and bactericides are given to illustrate the invention (all percentages and parts are by weight):

Example 1 Various 4-nitrosopyraz0les prepared as above in aqueous suspensions at dosages of 405 parts per million were. sprayed on various tomato plants. The suspensions were prepared with small amounts of a commercial surface-active dispersing agent (Emulphor EL which is a reaction product of ethylene oxide and castor oil) which was known to be non-toxic to the organisms under test. When the thus treated plants were sufiiciently dry, the plants, together with untreated (check) plants, were uniformly inoculated by spraying onto the foliage an aqueous suspension of spores of Alternarz'a solam', the fungus responsible for a serious leaf blight disease of this crop. The'plants were placed in an inoculation chamber at 75 F. and 99% humidity for '20 hours, after which they were removed to normal greenhouse conditions. After two days in the greenhouse, the efiectiveness of the various 4-nitrosopyrazoles was determined by counting the blight lesions on the tomato plants treated with the various 4-nitrosopyrazoles, and comparing with the number of blight lesions on the check plants which were not treated with the chemicals. The number of blight lesions on the plants treated with the various 4-nitrosopyrazoles and the number of blight lesions on the check plants are shown in columns 1 and 2 of the following table. The percent control by the various 4-nitrosopyrazoles is shown in the third column of the following table:

Blight Lesions per Plant Treatment Chemical Control Treated Check Plants Plants Per cent 1- PhenyI-3,5-dimethyl-4-nitrosopyrazole 0 379 100 l-(p-Tolyl) -3,5-dimethyl-l-nitrosopyrazole 0 379 100 l- (4-Chlorophenyl)-3,5-dimethyI-4-nitrosopyrazole. 0 379 100 l,3,5-Trimethyl-4-nitrosopyrazole 132 379 l-(4-Chlorophenyli-3-methyl-4-nitroso-5-n-hexylpyrazol 47 379 87. 5 l-(4-Bromophenyl)-3,5-dimethyL-l-nitrosopyrazole 0 379 100 l-(4-tert-Amylphenyl)-3,5-dimethyl-4-nitr0sopyrazole 0 379 100 l- (2, 4-Dichlorophenyl)-3,5dimethyli-nitrosopyrazole. 3 276 99 l-(25Dichlorophenyl)-3,5-dimethylA-nitrosopyrazole 0 276 100 3-Methyl-i-nitroso-5-phenylpyrazole 31 200 84. 5 3,5-Dimethyl-l-nitrosopyrazqle 89 195 54. 5 l- C arbamy1-3,5-dimethyl-4-mtrosopyrazole l 124 399 69 l- (4-Carboxypl1enyl)-3,5-dimethyl-4nitrosopyrazole 24 291 92 Copper salt of 1-(4-carboxyphenyl)-3,5-dimethyl-4-nitrosopyrazole... i9 291 93 5 3-MethyI-l-nitroso-S-ethoxypyrazole 91 291 69 l-(a-Naphthyl)-3,5dimethyl-*i-nitrosopyrazole- 0 3 .0 100 l-(4-Nitrophenyl)-3,5dimethyl-tnitrosooyrazole. 6 410 98. 5 l-(4-Thiocyanophenyl)-3,5-dimethyl-4-nitrosopyrazole. 2 252 99 l-(4-SultamylphenyDi,5-dimethyH-nitrosopyrazole 5 252 98 l-(m-Chlorophenyl)-3,5-dimethyl-4-nitrosopyrazole 0 252 100 l-(o-Chlorophenyl)-3,5-dimethyl-4-nitrosopyrazole O 252 100 l-(4-Iodophenyl)-3,5-dimethyi-4-nitrosopyrazole.. 10 575 98 l-(4-Fluorophenyl)-3,5-dimethyl-4-nitrosopyrazole 5 259 98 1-(p-Xenyl)-3,5-dimethyl-4-nitrosopyrazole.Q 78 252 69 l-(4-n-Butylphenyl)-3,5-dimethyi-initrosopyrazole 64 445 85 1-Phenyl-3-methyl-4-nitroso-5-methylaniliuopyrazole 0 265 100 Example II Pea seeds variety Laxtons Progress were tumbled with different dosages (16% and .64% of seed weight) of various 4-nitrosopyrazoles in finely ground form. .The seeds were planted in wet compost soil in flats which were kept in a moisture chamber at 60 F. and 99% humidity for six days. The flats were then placed in the.

greenhouse and kept there until the plants were 3 to 4 inches high. The fungicidal effectiveness of these 4-nitrosopyrazoles was determined by comparing the percentage oi treated seeds with 5 33, 627 (1043).

Copper salt 1-Phenyl-3-methyl-4-nitroso:5-methyl-anillnopyrazole- Chemical cana fungus spores on glass slides when treated with various of the 4-nitrosopyrazoles at 100, 10 and 1 parts per million (P. P. M.). The procedure used is that outlined in Phytopathology Percent Germination at- P. P. 10 P. P. M. l P. P. M.

Alt. 65

Sci. 0 Alt. Bel. Alt. Bel.

O66 GO :OO O O 0 006050969 Air. 801.

0 Alt. Alt. as Sci. Sci. as

o o o 0 Alt Alt. an Bcl. 0 Sci. 1 Sci. 0 Alt. as, 8,01. 01 o v o the percentage of untreated (check) seeds which germinated and developed into healthy plants. The results are shown in the following table:

. Example V The 4-nitrosopyrazoles have been shown to be.

Per Cent Germination, Dosage ot- Chemical 1- 4-Ohloro henyl)-35-dimethyl-4-nitrosopyrazo1e mo 54.4' lhenyl-a -dimethywnitroso yrazol 75.6 5&4 l- (i-tert-Amzlphcnyl)-3,5-dimcthyl-4-nitrosopyrazole 47. 2 45. 2 ll-Bromop enzD-i Mimethyl-i-nitrosopyrazole. 61. 6 63. 2 i 2 33 F 11? h fi fig fi l-amt "1 t; s f g 0 orop any 8 y OSODYI'BZO 8 Untreated (check) as. 6% to 31. 0%

Example III Five strips of cotton duck, 1" x 6", were soaked a in a 1% solution of 1-(4-chlorophenyl) -3,5-di'- methyl-4-nitrosopyrazole in acetone; similar strips were simultaneously soaked in acetone. After all strips were completely saturated they were removed from the baths, dried, and buried in compost soil. After five weeks the strips were removed from the soil. The strips which had been treated with the 4-nitrosopyrazole had tensile strengths of 138, 122, 127, 124, and 125 pounds per inch. The control strips were almost completely rotted and had no tensile strength.

Example IV The following-table lists the percent germination of Alternaria solani and Sclerotinia ameri- .bactericides by their ability to control Phytomonas tumejaciens, the casual agent of crown gall disease of apples, roses and many other plants.

One cc. aliquots of a culture of Phytomonas tumefaciens were dispersed in 9 cc. of sterile nutrient-dextrose broth and 1.1 cc. of chemical suspension added to give concentrations of the 4- nitrosopyrazoles of 1.6, 8.0, 40.0 and 200.0 P. P. M. Triplicate cultures containing each of the test chemicals were incubated sixteen hours at 27 0. During this period, tubes containing bacteria without test chemical became very turbid, indicating that the bacteria were capable of growth. The following table gives the lowest concentration 01' the chemical suspension added which prevented visible bacterial growthi Concentration of Chemical Preventing P. tum:-

' Chemical facims Growth P. P. M.

OQOOGIO The 4-nitrosopyrazoles have been further shown to be bactericides by their ability to control Xanthomonas phaseoli, the bacterium that causes common bacterial blight of beans. An actively growing 17-hour culture of bacteria in broth was suspended in warm nutrient-dextrose agar immediately before pouring about 20 cc. in each of several petri dishes 9 cm. in diameter. The bacterial cells grew readily in this medium as shown by uniform growth in all untreated dishes after 48 hours at 27 C.

The bactericidal-bacteriostatic action of the 4- nitrosopyrazoles was assayed by dipping sterile filter paper discs 13 mm. in diameter in aqueous suspensions of the chemical containing 2000, 400,

80 and 16 P. P. M. of the chemical and small amounts of Emulphor EL, and transferring the discs impregnated with chemical to the center of the dishes immediately after the agar hardened. The chemical diffused into the agar and those that were active prevented multiplication of the bac- The 4-nitrosopyrazole was superior to both bichloride of mercury and phenol. The zone of inhibition at 20 P. P. M. for the 4-nitrosopyrazole was larger than that for the standard bactericides at 2000 P. P. M.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. A fungicidal composition comprising an aqueous suspension of a 3,5-dimethyl-4-nitrosopyrazole in which the l-nitrogen of the pyrazole nucleus is attached to a member of the group consisting of hydrogen, alkyl, aryl and aralkyl radicals, said aqueous suspension containing a dispersing agent.

2. A fungicidal composition comprising an aqueous suspension of a 1-aryl-3,5-dimethyl-4- nitrosopyrazole, said aqueous suspension containing a dispersing agent.

3. A fungicidal composition comprising an aqueous suspension of a 1-chlorophenyl-3,5-dimethyl-4-nitrosopyrazole, said aqueous suspension containing a dispersing agent.

4. As a new compound, a 1-ch1orophenyl-3,5- dimethyl-4-nitrosopyrazole in which the chlorophenyl radical is selected-from the group consisting of 4-chlorophenyl, m-chlorophenyl, 0-

Diameter of Clear Zone for Chemical at Concentration 0i Chemical P. 4 00!. RM. 80P.P.M. 10?. P. M.

. Mm. Mm. Mm. Mm. l-Yhenyl-3,5-dimethyl-4-nitrosopyrazo1e 62 42 32 22 1,3,5-Trimethyl-4-nitrosopyrazole 90 80 65 29 1-(4-B romo phenyl) -3,5 dimethyl4 nitrosopyrazole. 90 30 22 0 l-(4-Carboxyphenyl)-3,5-dimethyl-4-nitrosopyramle. 39 31 24 17 3,5-Dimethyl-i-nitrosopyrazole 90 20 Check discs 0 0 chlorophenyl 2 -dichlorophenyl and 2 5-di- Ex m le VII a p chiorophenyl radicals.

In order to make a comparison with known germicides, a test was made with mercuric chloride, phenol and 1,3,5-trimethyl-4-nitrosopyrazole against Phytomonas tumefaciens. The procedure was similar to that outlined in Example VI except that the sterile discs were 9 mm. in diameter and the chemicals were suspended in water at concentrations of 2000, 200, 20, 2 and 0.2 P. P. M. Data on the diameter of the clear zones is given in the following table, which shows the relative ability of 1,3,5-trimethyl-4-nitros0pyrazole, mercuric chloride and phenol to prevent growth of Phytomonas tumefaciens in agar.

5. As a. new compound, l-(4-chlorophenyl) -3,5- dimethyl-4-nitrosopyrazole.

6. As a new compound, 1-(2,4-dichlorophenyl) 3,5-dimethyl-4-nitrosopyrazole.

7. As a new compound, 1- (2,5-dichlorophenyl) 3,5-dimethyl-4-nitrosopyrazole.

8. A fungicidal composition comprising an aqueous suspension of 1-(2,5-dichlorophenyl) 3,5-dimethyl-4-nitrosopyrazole, said aqueous suspension containing a dispersing agent.

9. A germicidal composition comprising a 3,5-dimethyl-4-nitrosopyrazole in which the 1- nitrogen of the pyrazole nucleus is attached to a member of the group consisting of hydrogen, alkyl, aryl and aralkyl radicals, said composition containing a surface-active dispersing agent.

10. A fungicidal composition comprising a 1-aryl-3,5-dimethyl-4-nitrosopyrazole and a surface-active dispersing agent.

NORMAN K. SUNDHOLM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Kyrides Jan. 8, 1948 OTHER REFERENCES Number 

1. A FUNGICIDAL COMPOSITION COMPRISING AN AQUEOUS SUSPENSION OF A 3,5-DIMETHYL-4-NITROSOPYRAZOLE IN WHICH THE 1-NITROGEN OF THE PYRAZOLE NUCLEUS IS ATTACHED A MEMBER OF THE GROUP CONSISTING OF HYDROGEN, ALKYL, ARYL AND ARALKYL RADICALS, SAID AQUEOUS SUSPENSION CONTAINING A DISPERSING AGENT. 